1. Field of the Invention
The invention pertains to gravitational separators for liquid purification, more specifically to an adaptor for an outlet opening of a septic tank, which diverts gas away from the outlet opening and traps and collects solid particles. The adaptor is small, light weight, and is easy to install in a new septic tank and in an existing septic tank when pumping out the tank.
2. Description of the Prior Art
It is necessary to reduce the percentage of solid particulate matter that is carried to a drain field by way of an outlet opening of a septic tank, as the particulate matter clogs the field and reduces its operational life. It is also necessary to prevent gasses generated by digestion of waste matter in the tank from carrying particulate matter to the opening. Many designs to overcome the two problems have been patented.
Some designs include walls which separate the input side of a tank from the output side and slow flow across the tank so that much of the heavier particulate matter sinks before it can be carried to the exit opening.
For example, U.S. Pat. No. 1,708,118, patented by C. L. Carpenter et al., Apr. 9, 1929 describes baffle plates over the inlet and outlet openings of the tank, and a vertical separator wall which rises from the bottom of the tank and terminates a short distance from the top wall of the tank to form an intervening gas passage above the level of the liquid in the tank.
The wall is spaced from the inlet and outlet openings, and has a relatively small transverse opening spaced from the bottom of the plate, at about the height of the bottoms of the baffles. Most of the digestion occurs on the input side of the separator wall where the heavy sediment settles. The finer sediment and relatively clear liquid passes through the transverse opening for further digestion and settling of another portion of the finer sediment before the liquid leaves through the outlet opening for the field.
Other designs include diverters under the outlet opening. For example, U.S. Pat. No. 2,143,248, patented Jan. 10, 1939 by L. Otto describes two inclined plates, each secured by one of its side edges to the wall of the tank below a vertical, semi-cylindrical conduit to the outlet of the tank. The plates are wider than the radius of the conduit, so that they extend further from the wall than the conduit. The plates are arranged in a Y shape, slightly spaced from one another whereby one passes below and across the bottom of the other, leaving a slit opening between them. Their top edges extend out as far on each side of the opening as the conduit.
The plates thus include a V which directs rising sediment and gasses in a direction that is parallel to the wall and to the right and left of the opening formed at the bottom of the semi-cylindrical conduit and the tank wall. The plates also permit some of the solid particulate matter which may collect on their upward surfaces to pass down through the slit.
This may work well at the start, but after time, the lighter particulate matter which tends to stick to a surface may clog the slit.
U.S. Pat. No. 4,832,846 patented May 23, 1989 by N. Gavin describes a horizontal flat wall diverter that extends inward and downward from the tank wall, just below a vertical, wall-mounted, semi-cylindrical outlet conduit. The flat wall is spaced from the bottom of the tank. The wall extends horizontally beyond the lower opening at the bottom of the conduit, so that the wall deflects rising gas bubbles away from the lower opening of the conduit.
U.S. Pat. No. 3,630,370 patented Dec. 28, 1971 by J. K. Quina, describes a biconic deflector, with its central axis concentric with the axis of the vertical pipe of a tee outlet opening of the septic tank. The biconic deflector is located immediately below the bottom end of the vertical pipe which extends down into the liquid in the tank, held in place below the pipe by holding means inserted into the bottom of the pipe.
The biconic deflector has a top and a bottom apex, each with a cross sectional area that is smaller than that of the bottom end of the pipe and the largest diameter of the deflector is larger than that of the bottom end opening of the pipe.
Gas bubbles resulting from fermentation, which rise in the liquid and carry solid particulate matter, are deflected outward by the lower cone, so that they flow up toward the region around the vertical pipe. The bottom end of the vertical pipe has unencumbered space about its periphery so that gas bubbles carrying solid particles will flow around the pipe and upward rather than dam up against an encumbrance and back up into the pipe.
In lieu of the axially oriented biconic deflector, a corbel, which is an upward and outward stepped projection, is molded on the concrete wall below the bottom end of the pipe. Bubbles flowing over the lower sloped face of the corbel are directed away from the wall and the pipe hanging in front of the wall as they move upward. Bubbles flowing over the top slope of the corbel travel to the unencumbered space around the vertical pipe, and upward.
U.S. Pat. No. 4,172,799, patented Oct. 30, 1979 by Perry, Jr. describes a biconic deflector comprising two conical members joined together at their bases with a suitable adhesive to form a substantially uniform di-cone member having a reinforced center section.
A pair of nylon flexible straps are each attached at one end to bosses just above the joined bases, and attached at their other ends to the bottom of a short coupling tube which closely fits into the inner diameter of the vertical pipe of an outlet tee of the septic tank.
The deflector is mounted on the pipe by inserting the tube upward into the vertical pipe until it stops against an internal rib in the pipe. When mounted on the pipe in the operative position, the biconic deflector is concentric with the central axis of the vertical pipe, spaced just below the lower opening of the pipe. The diameter of the base of the deflector is greater than the lower opening of the vertical pipe.
The flexible mounting provided by the nylon straps permits the conical deflector to be moved aside when a reamer is inserted in the vertical pipe to remove accumulated deposits from the pipe.
A freely movable weight of marble, glass or other suitable material within the biconic deflector assures that the deflector will return to concentricity with the pipe after it has been moved aside for a reaming operation. Holes in the top and bottom ends of the biconic deflector bleed trapped air to make sure that it stays flooded with liquid from the tank and will not float out of operative position.
When liquid enters the septic tank it sets up a flow through the outlet opening of the tank until the liquid in the tank drops back below the outlet opening. This flow, and the rising bubbles carries lighter, particulate matter through the outlet opening unless it is stopped by the deflector.
In general, biconic deflectors deflect gas bubbles reasonably well because the bubbles accelerate upwards past the large diameter base of the deflector upon their natural buoyancy, regardless of the current of liquid flow inward over the top of the biconic deflector into the vertical pipe.
The lighter particulate matter, however, carried solely by the current without upward boost of the bubbles, can be diverted inward over the surface of the upper cone and drawn upward into the vertical pipe of the outlet tee.
The lighter particulate matter may tend to stick to, and build up inside the vertical pipe, or continue on through the outlet opening of the tank and reduce the useful life of the leaching field.